Figure 2.

TEM images of (a) S. aureus, (b) S. aureus captured by Fe₃O₄@Au/DTNB/Au/4-MPBA, (c) S. pneumonia, and (d) S. pneumonia captured by Fe₃O₄@Au/DTNB/Au/4-MPBA. (e) Photographs of bacteria capture, the colonies on blood agar plates represent the amounts of remaining S. aureus and S. pneumonia in the supernatant after being captured by Fe₃O₄@Au/DTNB/Au/4-MPBA MNPs, the concentrations of bacteria ranged from 10⁴ cells mL⁻¹ to 10² cells mL⁻¹. (f) Images and (g) corresponding SERS intensities of Fe₃O₄@Au/DTNB/Au/4-MPBA-LFA with different concentrations of S. aureus and S. pneumonia: (i) 10⁵, 10⁵ cells mL⁻¹; (ii) 10⁵, 0 cells mL⁻¹; (iii) 0, 10⁵ cells mL⁻¹; and (iv) 0, 0 mL⁻¹.